Re: Plaster in Winter

[rob_tom@freenet.carleton.ca (Robert W. Tom)]

Claire;

I've never plastered in winter because I wouldn't attempt it in
winter. Working against the weather is too energy-intensive for my
liking.

But I can tell you with confidence that cementitious mixes which
are allowed to freeze before curing has taken place will be weak
and in many (most ? all ?) instances, will suffer permanent damage
(crumbling,spalling).

With concrete and cement mortar (ie stucco) mixes, calcium chloride
(maximum of 2% by dry mass of cement) is often used during cold
weather to accelerate setting. Heated enclosures are still
necessary during the curing period though if below-freezing temps
are anticipated. 

The use of calcium chloride for me, would be a choice of last resort.
It's use increases the potential for corrosion of galvanised and
aluminum components (ie lath and flashings)  and the potential for a
weakened end product.

If the straw is wet, (ie so wet that it is mouldy) then I would
hazard to say that it's too wet to plaster over. 

If you're near Habib Gonzales in Nelson (who I have cc'd), I'd
suggest it'd be well worth the cost of having him check the
moisture content of your straw for you if there is any doubt. 

I'd also suggest that the inclusion of some permanent moisture
sensors would be worthwhile. (see Habib's article in TLS or CMHC for
instructions on how to make them yourself or you can order some
from Rob Jolly in Edson, AB.

If worst comes to worst, the straw will still be great for compost
in the garden and you've already gotten a year of shelter out of them.



dalala@mars.ark.com wrote:
>My first question is, will it be safe to plaster now? We plan to shave off
>that moldy stuff but will the cement stucco inhibit further drying of the
>bales (already in place a year!)
>
>My second question is although our weather is fairly moderate the
>thermometer does drop below freezing on occasion. How does this affect the
>stucco?

---------- * ----------
Rob_Tom @ ncf.ca
Kanata, Ontario, Canada